Percolation of Core Melts at Lower Mantle Conditions

• Published in: Science (American Association for the Advancement of Science) Vol. 280; no. 5366; pp. 1059 - 1061
• Main Authors: Shannon, M. C., Agee, C. B.
• Format: Journal Article
• Language: English
• Published: Washington, DC American Society for the Advancement of Science 15.05.1998; American Association for the Advancement of Science; The American Association for the Advancement of Science
• Subjects: Climate; Crystalline rocks; Dihedral angle; Earth sciences; Earth, ocean, space; Exact sciences and technology; Experimental petrology; Geology; Grade Point Average; Homesteads; Internal geophysics; Iron alloys; Lower mantle; Mantle; Meteorites; Mineralogy; Networks; Perovskites; Rapid quenching; Scientific Concepts; Silicates; Solid-earth geophysics, tectonophysics, gravimetry; Temperature; Upper mantle; mineral assemblages; experimental studies; core; alloys; percolation; perovskite; oxides; lower mantle; iron; melts; high pressure; high temperature
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.280.5366.1059

Experiments at high pressure and temperature to determine the dihedral angle of core melts in lower mantle phases yielded a value of ∼71° for perovskite-dominated matrices. This angle, although greater than the 60° required for completely efficient percolation, is considerably less than the angles observed in mineral matrices at upper mantle pressure-temperature conditions in experiments. In other words, molten iron alloy can flow much more easily in lower mantle mineralogies than in upper mantle mineralogies. Accordingly, although segregation of core material by melt percolation is probably not feasible in the upper mantle, core formation by percolation may be possible in the lower mantle.